Compiled by: Ike Iyioke
SUMMARY: Exposure to chromium happens mostly from breathing contaminated workplace air, or
ingesting water or food from soil near waste sites. Chromium can cause allergic responses
in the skin, and high doses may damage the lungs or lead to death. Chromium has been found
in at least 115 of 1,300 National Priorities List sites identified by the EPA.
What is chromium?
Chromium is a steel-gray metallic element naturally found in rocks, soil, animals, and in volcanic dust and gases. It has three main forms -- chromium (0), chromium (III) and chromium (VI), the last two being the most important. In very small amounts, chromium (III) is an essential nutrient in our diet. It is believed to help insulin maintain normal glucose and cholesterol levels, and enhance fat metabolism. Both chromium (III) and (VI) are used for making steel and other alloys, bricks in furnaces, dyes and pigments, for chrome plating, leather tanning, and wood preserving.
Exposure to chromium:
Very small amounts of chromium (III) are found in everyday foods. Much larger amounts of chromium (III) and (VI) are released to the environment as a result of activities such as steel, refractory and chemical manufacturing; municipal incineration; and as constituent of sewage sludge. Industrial cooling towers and chrome plating facilities are sources of chromium (VI); and chromium (III) results from chromium ore refining, cement production and coal and oil combustion. Surface runoff, deposition from air, and discharges of municipal and industrial waste waters are sources of both forms of chromium in surface waters.
Chromium is primarily removed from the air by fallout and precipitation, and predominantly enters surface water or soil; but prior to deposition, chromium particles of small size may remain airborne for long periods of time and may be transported long distances. Most of the chromium (III) in surface waters eventually settles into sediments. Chromium (VI) tends to remain in solution due to its high water solubility and resistance to adsorption until it is eventually reduced to chromium (III) by organic matter present in the water.
Most chromium naturally present in soil is in an insoluble state which is relatively immobile and unavailable for plant uptake. Chromium in soil in soil may be transported to the atmosphere as dust. Chromium can persist in surface waters and soil for many years.
Higher exposures to chromium (III) and (VI) can occur from inhaling contaminated workplace air during stainless steel welding, chromate or chrome pigment production, chrome plating, and leather tanning. Other exposures can happen through handling or breathing sawdust from chromium treated wood; and breathing contaminated air, or ingesting water or food from soil near waste sites or industries that use chromium. Much greater exposure to chromium in terms of both frequency and concentration, occurs in people working in certain chromium industries and people who smoke cigarettes. Chromium may be found in tap water as a result of plumbing fittings.
Health effects:
All forms of chromium can be toxic at high levels, but chromium VI is most toxic. Breathing very high levels of chromium VI or for very long periods of time can irritate the nose, lungs, stomach and intestines. People who are allergic to it may also have asthma attacks after breathing high levels of either the VI or the III form.
Ingesting very large amounts of chromium can cause stomach upset and ulcers, convulsions, kidney and liver damage, and even death. Skin contact with liquids or solids containing chromium VI may lead to allergic reactions including severe redness and swelling or even skin ulcers.
Regulations to protect human health:
The Environmental Protection Agency (EPA) has set a maximum level for chromium III and VI in drinking water at 100 micrograms of chromium per liter of water. The Occupational Safety and Health Administration (OSHA) recommends that chromic acid and chromium VI compounds in the workplace air should not exceed 100 microgram per cubic meter of air for any period of time.
The Occupational Safety and Health Administration has established a maximum workplace exposure limit for chromium (II) and (III) of 500 micrograms per cubic meter averaged over an eight-hour day. The National Institute for Occupational Safety and Health (NIOSH) considers all chromium VI compounds to be potential occupational carcinogens and recommends an exposure limit of one microgram per cubic meter of air averaged over a 10-hour hour workday, 40-hour workweek. The National Research Council recommends a dietary intake of chromium III of not more than 50-200 micrograms per day since cases of chromium deficiency are rare in the US.
For more information about chromium toxicity, contact:
Mike Kamrin
Institute for Environmental Toxicology
C231 Holden Hall, MSU
Phone: 517-353-6469
Agency for Toxic Substances and Diseases Registry
Division of Toxicology
1600 Clifton Road NE
Mailstop E-29
Atlanta, GA 30333
Phone: 404-639-6000
